Adding custom fields to woocommerce checkout page disables place order button fu

I hope someone can help me as I can’t figure this one out. I’m trying to add this basic code to add a new field to the check out page however it seems to disable the place order button. Here is the code

woocommerce_form_field( 'my_field_name', array(
    'type'          => 'text',
    'class'         => array('my-field-class form-row-wide'),
    'label'         => __('Were you assisted with this order?'),
    'placeholder'   => __('Please enter the name of your rep here'),
    ), $checkout->get_value( 'my_field_name' ));

echo '</div>';

Note: I’m using snippets plugin to insert